Re: questions about light

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1 total messages Started by PHYS2SHS Wed, 27 Apr 1994 19:57

#1575

Author: PHYS2SHS
Date: Wed, 27 Apr 1994 19:57

23 lines
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>Just a comment about your answer to 2. below
>
>
>> >2. If light is a particle, when it leaves a flashlight why doesn't it
>> >have enough momentum to push the flashlight backward?
>>
>> No mass, no momentum, no recoil.
>>
>Though light doesn't have mass it still has momentum.  This is  the
>principal behind the light sail for spacecraft.  The momentum is given by
>
>p=h x frequency /c where h = Planck's constant and c is the speed of light.
>
>If the flashlight were not affected by forces such as gravity and friction
>at its location it would indeed move backwards under the influence of the
>weak force exerted by the photons.
>
>Ted van Nostrand
>Holy Heart High School
>St. John's, NF, Canada

Thank's for the correction... Sorry about the misinformation (I was not think
about light pressure ....  GRSnow

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